You can use PNT Converter App

GPS/FISH FINDER Furuno 1670/1870 and 1670f /1870f export waypoints and routes to PNT file extension. PNT Converter application converts these files into GPX and TXT extension files!

https://play.google.com/store/apps/d...savvas.pnt2gpx

See CF Post https://www.cruisersforum.com/forums/f134/transfering-waypoints-258797.html#post3753234